60 THE VOYAGE OF H.M.S. CHALLENGER. 



The adductor minimi digiti was very similar to the same muscle in Cuscus. It 

 took origin from the whole length of the outer margin of the raphe, and also from the 

 bases of the third and fourth metatarsal bones, and was inserted into the inner side of 

 the base of the proximal phalanx of the Uttle toe. 



The adductor indicia arose from the inner margin of the distal two-thirds of the 

 raphe, and converging towards the index was inserted into the outer side of the base of 

 its first phalanx. 



The adductor hallucis was a very powerful muscle which arose from the base of the 

 middle metatarsal bone, from the proximal third of the inner margin of the fibrous raphe 

 and from a condensation of the fascia covering the flexor brevis indicis, and which might 

 even be regarded as a second raphe. It was inserted upon the outer aspect of the first 

 phalanx of the hallux, partly into the sesamoid bone, and partly into the extensor 

 tendon. 



In the first specimen, therefore, the line towards which the adductor muscles operated 

 was one drawn through the index, as in Cuscus, whilst in the second specimen, the 

 annular digit constituted the centre for these movements. 



But it becomes a point of interest to inquire into the manner in which the raphe has 

 become attached in the one case to the inner side of the base of the ring digit, and in the 

 other case into the outer side of the index digit. If we refer back to the condition in 

 Dasyurus, some light will be thrown upon this. In this animal the adductor minimi 

 digiti and adductor indicis arise from a central raphe which has no distal attachment. 

 From the deep surface of this the adductor annularis takes origin. Now let us suppose 

 this last muscle to be converted into fibrous tissue, and a condition resembling that in 

 the second specimen, the Vulpine Phalanger, would result. In place of this, however, say 

 that the adductor indicis degenerates into fibrous tissue, in this case a state of affairs 

 similar to that in Cuscus and the first specimen of the Vulpine Phalanger would be 

 produced. A careful study of these feet renders it very probable that the fibrous raphe 

 gains its distal attachment in this way. 



Intermediate layer. — The flexores breves are well marked, and are five in number — 

 one for each toe. With the exception of that for the little toe which is only represented 

 by a fibular head, each muscle is composed of two slips. The flexor brevis hallucis is 

 more powerful than the corresponding muscle in Cuscus. The inner head of the flexor brevis 

 medii apparently contains in its midst the fibres of the second dorsal interosseus which is 

 absent as an independent and separate muscle. Again, the absent inner head of the 

 flexor brevis minimi digiti is in all probability fused with the fourth dorsal interosseus, as 

 this muscle projects more into the sole than any of its neighbours. 



Dorsal layer. — This group includes: (1) the abductor hallucis; (2) the abductor 

 minimi digiti and abductor ossis metatarsi minimi digiti ; (3) the dorsal interossei. 



The abductor hallucis is very poorly developed as compared with the corresponding 



